The present invention relates to a method of forming a coil and a coil winding apparatus for carrying out the coil winding method.
When forming a coil having a polygonal cross section, i.e., a so-called Vicks coil, by winding a wire, for example, for a flat motor, a coil winding jig holding a coil form between a pair of flanges must be rotated while a first layer, a second layer, . . . and n-th layer are sequentially wound onto the form. The spirals of the wire in the second layer and the following layers must be formed between the spirals of a wire in the underlying layer in a mutually interposed arrangement to form each layer.
Since a fixed tensile force is exerted on the wire when winding the wire into the coil, the first spiral of the second layer is forced to fall between the last spiral of the first layer underlying the second layer and a flange of the machine and, consequently, the spirals of the second layer tend not to be formed regularly in a mutually interposed arrangement over the first layer. This results in an irregular arrangement of spirals of the wire in the third layer and the following layers, so that a random coil is formed.
Further, since a tensile force is exerted on the wire when the wire is wound on the coil form, the coil binds onto the coil form with the result that a large force must be applied to the coil to remove the coil from the coil form.